Wellbore logging system

ABSTRACT

A logging system for use in a borehole formed in an earth formation, comprising a tubular element to be installed in the borehole, and a logging member including a conduit having an inlet opening and being movable in radial direction of the tubular element between a retracted position in which the logging member is substantially arranged within the tubular element and an extended position in which the logging member extends beyond the tubular element so that said inlet opening is in fluid communication with the earth formation when the tubular element is installed in the borehole, the logging system further comprising an activating device for moving the logging member between the retracted position and the extended position thereof.

FIELD OF THE INVENTION

[0001] The invention relates to a logging system for use in a boreholeformed in an earth formation.

BACKGROUND OF THE INVENTION

[0002] Generally, in the practice of wellbore drilling each furthersection of a wellbore is drilled after the previously drilled wellboresections are cased with wellbore casing. After completing drilling ofthe further section, a logging tool is lowered by wireline through thepreviously installed casing and into the newly drilled section so as toconduct a measurement of a downhole parameter. An example of suchlogging tool is a formation pressure test/sampling tool for measuringthe pressure or composition of fluid present in the earth formation.Such tool is provided with a conduit which is pushed into the boreholewall a short distance so as to create fluid communication between theearth formation fluid and a fluid chamber of the tool.

[0003] A drawback of such wireline logging method is the requiredadditional drilling rig time during lowering and operating the loggingtool. A further drawback is that there is a danger that the logging toolgets blocked in the open wellbore section. Moreover, it may not bepossible to insert the logging tool into a significant part of the newlydrilled wellbore section, for example in case of a highly inclined orhorizontal borehole sections. As a consequence valuable information onthe surrounding formation cannot be obtained.

[0004] It is an object of the invention to provide an improved loggingsystem which overcomes the drawbacks of the conventional system.

SUMMARY OF THE INVENTION

[0005] In accordance with the invention there is provided a loggingsystem for use in a borehole formed in an earth formation, comprising atubular element to be installed in the borehole, and a logging memberincluding a conduit having an inlet opening and being movable in radialdirection of the tubular element between a retracted position in whichthe logging member is substantially arranged within the tubular elementand an extended position in which the logging member extends beyond thetubular element so that said inlet opening is in fluid communicationwith the earth formation when the tubular element is installed in theborehole, the logging system further comprising an activating device formoving the logging member between the retracted position and theextended position thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]FIG. 1 schematically shows an embodiment of the logging system ofthe invention in a first mode of operation thereof.

[0007]FIG. 2 schematically shows the embodiment of FIG. 1 in a secondmode of operation thereof.

DETAILED DESCRIPTION

[0008] The logging system of the invention saves valuable drilling rigtime since the tubular element forms an integral part of the loggingsystem and is to be lowered into the borehole anyway. Thus there is noneed to separately lower a logging tool into the borehole by wirelineduring periods between lowering/installing the tubular element anddrilling the further wellbore section. Also, lowering of the tubularelement into highly inclined or horizontal wellbore sections can be donemore easily than lowering of a wireline into such sections. A furtheradvantage of the logging system according to the invention is that bymoving the logging member to its retracted position the tubular elementcan be lowered into the borehole without being hampered by the loggingsystem and without the risk of damage to the logging member. Further, bymoving the logging member to its extended position after the tubularelement is installed in the borehole, a characteristic of the earthformation fluid (e.g. pressure or composition) can be determined in alogging run.

[0009] Suitably the activating device is removably arranged within thetubular element. Thus, after lowering of the tubular element into theborehole and determination of the fluid characteristic, the activatingdevice can be removed from the tubular element and retrieved to surfaceso that the interior of the tubular element is free from obstacles inorder to allow passage of wellbore tools or selected fluids through thetubular element.

[0010] Preferably the tubular element is one of a wellbore casing, awellbore liner and a drill string.

[0011] The invention will be further described in more detail and by wayof example with reference to the accompanying drawings.

[0012] Referring to FIGS. 1 and 2 there is shown a wellbore casing 1arranged in a borehole 2 formed in an earth formation 4, which casing 1has not yet been cemented in the borehole 2 but is suspended from adrilling rig (not show) at surface. The casing 1 includes an uppercasing section 6, an intermediate casing section 8 connected to theupper casing section 1 by connector 9, and a lower casing section 10connected to the intermediate casing section by connector 11. Theintermediate casing section 8 is provided with an opening 12 in which aprimary pad 14 and a telescoping member 16 are arranged. The pad 14 isof cylindrical shape and has an outer surface 14 a facing the boreholewall and an inner surface 14 b facing the interior of the casing section8. At least an end part of the primary pad at the side of the outersurface 14 a is made of elastomeric material.

[0013] The telescoping member 16 connects the primary pad 14 to thecasing section 8, and is arranged to perform a telescoping movement inradial direction (of the casing 1) so as to move the primary pad 14between a retracted position wherein the primary pad 14 is locatedsubstantially within the outer radius of the casing section 8 and anextended position wherein the primary pad 14 extends beyond the outerradius of casing section 8 and the outer surface 14 a contacts the wallof the borehole 2. Furthermore, the telescoping member 16 seals theprimary pad 14 relative to the casing section 18.

[0014] The primary pad 14 is provided with a bore 18 extending in radialdirection of the casing section 8, in which a conduit 22 is arranged ina manner allowing the conduit 22 to slide through the bore 18 a selectedstroke. The conduit 22 has at its inner end a shoulder 24 which, when incontact with the inner surface 14 a, prevents further outward sliding ofthe conduit 22. A compression spring 25, arranged between the shoulder24 and the inner surface 14 b of the primary pad 14, biases the conduit22 to a radially inward position thereof. The conduit 22 is internallyprovided with a ball valve 26 including a ball 28 biased against a valveseat 30 by a spring 32. The ball valve 26 prevents flow of fluid fromthe exterior of the casing section 8 to the interior thereof when theball 28 is biased against the valve seat 30.

[0015] The primary pad 14 is biased to its retracted position by a leafspring 29 extending along the outer surface of the casing section 8 andbeing connected at opposite ends thereof to the casing section 8. Theleaf spring 8 is provided with an opening (not shown) for passage of theconduit 22 therethrough as the conduit 22 slides outwardly through thebore 18.

[0016] An activating device 34 is removably arranged within the casingsection 8 and latched to the casing wall by a latching assembly (notshown). The activating device 34 includes a secondary pad 36 ofcylindrical shape and made of elastomeric material, which secondary pad36 is arranged concentrically relative to the primary pad 14 and a jack38 arranged to bias the secondary pad 36 against the primary pad 14 soas to move the primary pad 14 between the retracted position thereof andthe extended position thereof. The activating device 34 furthermoreincludes a support member 40 for supporting the jack 38 against theinner surface of the casing section 8, an electric motor 42 foroperating the jack 38, a fluid chamber 44 provided with a fluid pressuregauge (not shown), an electronic control/memory unit (not shown) forcontrolling the electric motor 42 and the pressure gauge and for storingpressure readings of the pressure gauge, and a battery (not shown) forpowering the control/memory unit and the electric motor 42. Thesecondary pad 36 is provided with a tube 46 extending concentricallythrough the secondary pad 36 and arranged to bias the ball 28 away fromthe valve seat 30 and to provide fluid communication between the conduit22 and the fluid chamber 44 when the secondary pad is biased against theprimary pad 14.

[0017] The primary pad 14, the secondary pad 36, and the conduit 22 aredimensioned such that, upon movement of the secondary pad 36 against theprimary pad 14, the secondary pad 36 pushes against the conduit 22 whichthereby slides in radially outward direction through the bore 18 and theopening of the leaf spring 29 until the shoulder 24 contacts the innersurface 14 b of the primary pad 14.

[0018] Normal operation of the assembly referred to in FIGS. 1 and 2 ishereinafter described, whereby FIG. 1 shows the primary pad 14 in theretracted position and FIG. 2 shows the primary pad in the extendedposition.

[0019] During normal operation the activating device 34 is latched intothe casing section 8 by means of the latching assembly, and the casingsections 6 and 10 are connected to casing section 8 by the respectiveconnectors 9, 11. Then the casing 1, with the primary pad 14 in theretracted position, is lowered into the borehole 2. Lowering is stoppedwhen the primary pad 14 arrives at a selected depth in the boreholewhere it is desired to conduct a pressure measurement of earth formationfluid such as oil or water. A wireless control system (not shown) atsurface is then operated so as to induce the control/memory unit tooperate the electric motor 42 so that the motor 42 induces the jack 38to bias the secondary pad 36 against the primary pad 14. The primary pad14 thereby moves from the retracted position to the extended position inwhich the outer surface 14 a of the primary pad 14 is biased against theborehole wall (FIG. 2). Simultaneously the secondary pad 36 pushesagainst the conduit 22 so that the latter protrudes through the openingof the leaf spring 29 and extends a short distance into the boreholewall, and the tube 46 biases the ball 28 away from the valve seat 30 andthereby provides fluid communication between the conduit 22 and thefluid chamber 44. As a result the fluid chamber 44 communicates withfluid present in the earth formation. The control/memory unit thenoperates the fluid pressure gauge so as to measure the pressure of theformation fluid and to store the resulting pressure data in theelectronic memory.

[0020] The electric motor 42 is then induced to retract the jack 34 soas to move the secondary pad 36 radially inward. As a result the primarypad 14 also moves radially inward due to the biasing force from the leafspring 29. The primary pad 14 and secondary pad 36 remain in contactuntil the primary pad 14 reaches its retracted position. Furtherradially inward movement of the secondary pad 36 causes secondary pad 36to become displaced from the primary pad 14, and the tube 46 to becomedisplaced from the ball 28 so that the spring 18 biases the ball 28against the valve seat 30 thereby closing the ball valve 26.

[0021] If further earth formation fluid pressure measurements atdifferent borehole depths are desired, the casing 1 is raised or loweredthrough the borehole 2 so as to relocate the primary pad 14 in theborehole 1 at the desired depths. The procedure as describedhereinbefore is then repeated.

[0022] After completing the desired pressure measurements, a suitableretrieving device (not shown) is lowered through the casing 1 to theactivating device 34 in order to unlatch the activating device 34 fromthe casing section 8 and to retrieve the activating device 34 tosurface. The pressure data is then read out from the electronic memoryat surface.

[0023] If no further earth formation fluid pressure measurements are tobe conducted the casing 1 is cemented in the borehole 1. In case theborehole 2 is to be further drilled, the latching assembly is drilledout of the casing 1 before commencement of further drilling.

[0024] Instead of reading the pressure data from the electronic memoryafter retrieval of the activating device 34 to surface, the pressure canalternatively be read by extending a data transfer line (e.g. anelectric conductor) from surface to the activating device 34 andtransferring the data in the form of electric signals through the datatransfer line to surface while the activating device 34 is still latchedto the casing 1.

We claim:
 1. A logging system for use in a borehole formed in an earthformation, comprising a tubular element to be installed in the borehole,and a logging member including a conduit having an inlet opening andbeing movable in a radial direction of the tubular element between aretracted position in which the logging member is substantially arrangedwithin the tubular element and an extended position in which the loggingmember extends beyond the tubular element so that said inlet opening isin fluid communication with the earth formation when the tubular elementis installed in the borehole, the logging system further comprising anactivating device for moving the logging member between the retractedposition and the extended position thereof.
 2. The logging system ofclaim 1 , wherein the logging member includes a pad which extendsagainst the borehole wall when the tubular element is installed in theborehole and the logging member is in its extended position.
 3. Thelogging system of claim 2 , further comprising a telescoping memberinterconnecting the pad and the tubular element and being arranged toperform a telescoping movement so as to move the logging member betweenthe retracted position and the extended position thereof.
 4. The loggingsystem of claim 2 , wherein the pad forms a primary pad and theactivating device includes a secondary pad arranged to bias the loggingmember from the retracted position to the extended position thereof. 5.The logging system of claim 4 , wherein the activating device isprovided with a fluid chamber, and the secondary pad is provided with atube arranged to provide fluid communication between said conduit andthe fluid chamber when the secondary pad is biased against the loggingmember.
 6. The logging system of claim 4 , wherein said conduit isprovided with a valve preventing flow of earth formation fluid into thetubular element when the valve is in the closed position, and whereinthe secondary pad is arranged to open the valve when the secondary padbiases against the logging member.
 7. The logging system of claim 1 ,wherein the activating device is removably arranged within the tubularelement.
 8. The logging system of claim 1 , wherein the activatingdevice is provided with means for determining a characteristic of earthformation fluid entering the conduit when said inlet opening is in fluidcommunication with the earth formation.
 9. The logging system of claim 8, wherein said characteristic includes a pressure of the earth formationfluid entering the conduit.
 10. The logging system of claim 1 , whereinat least one of the logging member and the activating device forms anRFT logging tool.
 11. The logging system of claim l, wherein the tubularelement forms one of a wellbore casing, a wellbore liner and a drillstring.
 12. The logging system of claim 1 , wherein the tubular elementis internally provided with a latching assembly for latching theactivating device to the tubular element.